The invention relates to a fuel additive and fuel composition containing the same. More in particular, the invention relates to a fuel additive acting as a detergent and as a lubricity additive in fuel compositions, in particular in low-sulphur fuel compositions, more in particular in low-sulphur diesel fuel compositions.
From EP-A-0,798,364 fuel additives are known, based on either the salt of a carboxylic acid and an aliphatic amine, or an amide obtained by dehydration-condensation between a carboxylic acid and an aliphatic amine. The additive can be incorporated into a fuel, i.e., a diesel fuel, and thus reduce the amount of deposit in the injection nozzle of a compression-ignition diesel engine, improve lubricity of the diesel fuel, and reduce wear of the fuel injection pump of the engine. In short, the additive acts as a detergent and as a lubricity additive. Fuel additives acting both as detergent and as lubricity additive are rare. It would therefore be desirable to extend the range of such additives, or better still, to provide improved additives acting both as detergent and lubricity additive.
Accordingly, the invention provides the use of a poly(hydroxycarboxylic acid)amide or -ester derivative of general formula I: 
wherein R is the residue of an amine, an aminoalcohol or a polyol linked to the or each poly(hydroxycarboxylic acid) via an amide or ester linkage; R1 is hydrogen or optionally substituted hydrocarbyl group containing up to 50 carbon atoms; A is an optionally substituted hydrocarbyl group; n is from 1-100, preferably 1-10 and p is from 1-5, as a fuel additive acting as a detergent and as a lubricity additive in fuel compositions.
Moreover, the invention provides a fuel oil composition comprising of a major amount of a fuel oil, and a minor amount of an the additive as well as a additive concentration for use in a fuel oil composition.
As used herein, the term xe2x80x9chydrocarbylxe2x80x9d represents a radical formed by removal of one or more hydrogen atoms from a carbon atom of a hydrocarbon (not necessarily the same carbon atoms in case more hydrogen atoms are removed). In case of R1 useful hydrocarbyls are aromatic, aliphatic, acyclic or cyclic. Preferably, the hydrocarbyls are aryl, cycloalkyl, alkyl or alkenyl, in which case they may be straight-chain or branched-chain. Representative hydrocarbyls include phenyl, naphthyl, methyl, ethyl, butyl, pentyl, methylpentyl, hexenyl, dimethylhexyl, octenyl, cyclooctenyl, methylcyclooctenyl, dimethylcyclooctyl, ethylhexyl, octyl, isooctyl, dodecyl, hexadecenyl, eicosyl, hexacosyl, triacontyl and phenylethyl. The optionally substituted R1 is preferably aryl, alkyl or alkenyl containing up to 50 carbon atoms, especially from 7 to 25 carbon atoms such as heptyl, octyl, undecyl, lauryl, heptadecyl, heptadenyl, heptadecadienyl, stearyl, oleyl, or linoleyl. Other examples of R1 include C4-8 cycloalkyl such as cyclohexyl; polycycloalkyls such as polycyclic terpenyl groups which are derived from naturally occurring acids such as abietic acid; aryl such as phenyl; aralkyl such as benzyl; polyaryl such as naphthyl, biphenyl, stibenyl and phenylmethylphenyl.
When the hydrocarbyl is substituted, it may contain a functional group such as carbonyl, carboxyl, nitro, hydroxy, halo, alkoxy, tertiary amino (no Nxe2x80x94H linkages), oxy, cyano, sulfonyl and sulfoxyl. The majority of the atoms, other than hydrogen, in substituted hydrocarbyls are carbon, with the heteroatoms (e.g., oxygen, nitrogen and sulphur) representing only a minority, about 33% or less, of the total non-hydrogen atoms present.
Those skilled in the art will appreciate that functional groups such as hydroxy, halo, alkoxy, nitro and cyano in a substituted hydrocarbyl group will displace one of the hydrogen atoms of the hydrocarbyl, whilst functional groups such as carbonyl, carboxyl, tertiary amino (xe2x80x94Nxe2x80x94), oxy, sulfonyl and sulfoxyl in a substituted hydrocarbyl group will displace a xe2x80x94CHxe2x80x94 or xe2x80x94CH2xe2x80x94 moiety of the hydrocarbyl.
In xe2x80x9coptionally substituted hydrocarbyl of 1 to 50 carbon atomsxe2x80x9d, the expression xe2x80x9c1 to 50 carbon atomsxe2x80x9d represents the total number of carbon atoms in the optionally substituted hydrocarbyl group. The same applies to xe2x80x9coptionally substituted hydrocarbylxe2x80x9d of lower numbers of specified carbon atoms.
The or each radical R1 is preferably unsubstituted or subtituted by a group selected from hydroxy, halo or alkoxy group, especially C1-4 alkoxy. Preferred R1 are residues of a stearyl, oleyl, 12-hydroxystearyl, 12-hydroxyoleyl, and that derived from naturally occurring oil such as tall oil fatty acid.
The moiety represented by A may be an aromatic, aliphatic or cycloaliphatic group. It is preferably an arylene, alkylene or alkenylene group, especially one containing from 4 to 25 carbon atoms with at least 4 carbon atoms between the oxygen atom and carbonyl group. More preferably it is a saturated alkylene group or an arylene group. When n is greater than 1, this moiety may be the same or different. This moiety may carry other substituents which do not confer water solubility on the molecule, such as halogen and C1-4 alkoxy. Preferred examples of Oxe2x80x94Axe2x80x94COxe2x80x94 are 12-oxystearyl, 12-oxyoleyl and 6-oxycaproyl. More preferred examples are saturated groups such as 12-oxystearyl, 6-oxycaproyl.
The amines, aminoalcohols or polyols which react with poly(hydroxycarboxylic acid) to form products of formula I are as defined in WO97/41092. For example, various amines and their preparations are described in U.S. Pat. Nos. 3,275,554, 3,438,757, 3,454,555, 3,565,804, 3,755,433 and 3,822,209. Complex amines such as xe2x80x9cStarburstxe2x80x9d (Trade Mark) dendrimers may be used, e.g. the compound of formula [CH2N((CH2)2CONH (CH2)2NH2)2]2.
Examples of polyols include ethylene glycol, glycerol, trimethylolethane, trimethylolpropane, 1,2-butanediol, 2,3-hexanediol, 2,4-hexanediol, pinacol, erythritol, arabitol, sorbitol, mannitol, pentaerythritol, dipentaerythritol and tripentaerythritol. Preferred derivatives of formula I are those wherein the compound of R(H)p, of which R represents the residue, has the general formula II:
HX[(CR2R2)aO]b[(CR3R3)cNR4]d[R9)s(CHR3)eR5]f[(CR3R3)g(R6)h]iR7xe2x80x83xe2x80x83(II)
wherein X is O or NR4; each R2 independently represents hydrogen, hydrocarbyl of 1 to 10 carbon atoms or hydrocarbyl of 1 to 10 carbon atoms substituted by at least one hydroxy group; each R3independently represents hydrogen or hydrocarbyl of 1 to 10 carbon atoms; each R4 independently represents hydrogen or hydrocarbyl of 1 to 10 carbon atoms; R5 represents a C5-7 cycloalkanediyl xe2x80x94NHxe2x80x94 or 1,4-piperazinediyl moiety optionally substituted by one or more hydrocarbyl groups of 1 to 10 carbon atoms; each R6 independently represents NR8 or CHR8; R7 represents hydrogen, hydrocarbyl of 1 to 30 carbon atoms or a xe2x80x94CO (CHOH)t(CR3R3)j(NR3)k(CR3R3)1OH group; R8 represents a xe2x80x94(CR3R3)rNR4R7 group; R9 represents a C5-7 cycloalkanediyl moiety optionally substituted by one or more hydrocarbyl groups of 1 to 10 carbon atoms; a is 1 to 10; b is 0 to 10; c is 1 to 10; d is 0 to 10; e is 1 to 10; f is 0 or 1; g is 1 to 10; h is 0 or 1; i is 0 to 10; j is 1 to 10; k is 0 or 1; 1 is 1 to 10; r is 1 to 10; s is 0 or 1, and t is 0 or 1; and integers b, d, f and i indicate numbers of associated moieties present, and the various moieties [(CR2R2)aO], [(CR3R3)cNR4], [(CHR3)eR5] and [(CR3R3)g(R6)h] may be in any linear order.
Preferably in formula II X is O or NR4, each R2 independently represents hydrogen, C1-4 alkyl or C1-4 hydroxyalkyl, each R3 independently represents hydrogen or C1-4 alkyl, each R4 represents hydrogen or methyl, R5 represents a 1,4-piperazinediyl moiety or a cyclohexanediyl xe2x80x94NHxe2x80x94 moiety optionally substituted by up to three methyl groups, each R6 independently represents NR8 or CHR8, R7 represents hydrogen, methyl or a xe2x80x94CO(CHOH)t(CHR3)j(NR3)k(CHR3)1OH group, R8 represents a xe2x80x94(CHR3)rNHR7 group, R9 represents a cyclohexanediyl moiety optionally substituted by up to three methyl groups, a is 1 to 5, b is 0 to 5, c is 1 to 6, d is 0 to 5, e is 1 to 5, f is 0 or 1, g is 1 to 5, h is 0 or 1, i is 0 to 5, j is 1 to 5, k is 0 or 1, 1 is 1 to 5, r is 1 to 5, s is 0 or 1 and t is 0 or 1.
Advantageously, X is O or NH, each R2 independently represents hydrogen, methyl or hydroxymethyl, each R3 independently represents hydrogen or methyl, each R4 represents hydrogen or methyl, R1 represents a 1,4-piperazinediyl moiety or a cyclohexanediyl xe2x80x94NHxe2x80x94 moiety optionally substituted by up to 3 methyl groups, each R6 independently represents NR8or CHR8, R7 represents hydrogen, methyl, or a CO(CHOH)t(CHR3)j(NR3)k(CHR3)1OH group, R8 represents a (CHR3) rNHR7 group, a is 2 or 3, b is 0 to 3, c is 2 to 6, d is 0 to 4, e is 3, f is 0 or 1, g is 2 or 3, h is 1, i is 0 or 1, j is 1 to 4, k is 0 or 1, 1 is 1 to 4, r is 1 or 2, s is 0 or 1 and t is 0 or 1.
Examples of preferred such moieties R when p=1 are the following:
xe2x80x94NHCH2CH2N(CH2CH2NH2)2; xe2x80x94O(CH2C(CH2OH)2O)bH where b is 1 to 3, preferably 1; xe2x80x94NH(CH2CH2NH)dH where d is 1 to 4; xe2x80x94NHCH2CH2NHCH2CH2OH; xe2x80x94NH(CH2)cNH2, where c is 2 to 6, preferably 2 to 4; xe2x80x94NH(CH2)3NH(CH2)2NH(CH2)3NH2; xe2x80x94NH (CH2CH2O)2CH2CH2NH2; xe2x80x94NH(CH2CH2O)2H; xe2x80x94NH(CH2)3(1,4-piperazinediyl)(CH2)3NH2; xe2x80x94NH(1,4-cyclohexanediyl)CH2(1,4-cyclohexanediyl)NH2; xe2x80x94NHCH2(1,3,3-trimethyl-5-aminocyclohexyl); xe2x80x94NH(CH2CH2CH2NH)2H; xe2x80x94NH(CH2)3CH(CH2NH2)(CH2)4NH2; xe2x80x94NHCH2C(CH3)2CH2NH2; xe2x80x94NH(CH2)3N(CH3)2; xe2x80x94NHCH2CH2N(CH2CH2NHCO(CH2)2CH(CH3)OH)2; xe2x80x94NHCH2CH2N(CH2CH2NHCOCH2N(CH3)CH2CH2OH)2.
Examples of preferred such moieties R when p=2 are xe2x80x94NH(CH2CH2NH)3xe2x80x94 and xe2x80x94NHCH2CH2N(CH2CH2NH2)CH2CH2NHxe2x80x94
Most preferably, R(H)p is selected from the group consisting of glycerol, pentaerythritol, dipentaerythritol, tripentaerythritol, ethylenediamine, dietheylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and tris(2-aminoethyl)amine.
The preparation of poly(hydroxycarboxylic acid) and its amide or ester derivatives is known and is described, for instance, in patent documents EP164817, WO95/17473, WO 96/07689, U.S. Pat. No. 5,536,445, GB2001083, GB1342746, GB1373660, U.S. Pat. No. 5,000,792, U.S. Pat. No. 4,349,389.
The poly(hydroxycarboxylic acid) moiety in formula I may be prepared by the interesterification of one or more hydroxycarboxylic acids together with a non-hydroxycarboxylic acid which acts as a chain terminator. The hydroxyl group in the hydroxycarboxylic acid and the carboxylic group in either carboxylic acid, may be primary, secondary or tertiary in character. Examples of suitable hydroxycarboxylic acids are 12-hydroxystearic acid, 12-hydroxy-9-oleic acid (ricinoleic acid), 6-hydroxycaproic acid, especially 12-hydroxystearic acid. Commercial 12-hydroxystearic acid normally contains up to 15% wt of stearic acid and other non-hydroxycarboxylic acids as impurities and can conveniently be used without further admixture to produce a polymer of molecular weight about 1000-2000. Where the non-hydroxycarboxylic acid is separately introduced, the proportion which is required in order to produce a polymer or oligomer of a given molecular weight can be determined either by simple experiment or by calculation.
The interesterification of the hydroxycarboxylic acid and the non-hydroxycarboxylic acid may be effected by heating the starting materials either or not in a suitable hydrocarbon solvent such as toluene or xylene and azeotroping off the formed water. The reaction may be carried out at temperature up to 250xc2x0 C., conveniently at the reflux temperature of the solvent. Where the hydroxy group is secondary or tertiary, the temperature employed should not be so high as to lead to dehydration of the acid molecule. Catalysts for the esterification, such as p-toluenesulphonic acid, zinc acetate, zirconium naphthenate or tetrabutyl titanate, may be included, with the objective of either increasing the rate of reaction at a given temperature or of reducing the temperature required for a given rate of reaction.
The subsequent amidation with amines, aminoalcohols or esterification with polyols may be carried out according to methods known to those skilled in the art, by heating the poly(hydroxycarboxylic acid) with amines, aminoalcohols or polyols either or not in a suitable hydrocarbon solvent such as toluene or xylene and azeotroping off the formed water, with or without catalysts such as p-toluenesulphonic acid, zinc acetate, zirconium naphthenate or tetrabutyl titanate.
In fact, various patent documents disclose poly(hydroxycarboxylic acid) amide or ester derivatives, albeit for uses other than in fuels. For instance, GB1373660 discloses poly(hydroxycarboxylic acid) amide derivatives with amines such as 3-dimethylamino-propylamine and ethylenediamine for use as dispersing agent in dispersions of pigments in organic liquids. GB2001083 discloses poly(hydroxycarboxylic acid) amide derivatives with poly(ethyleneimine) (PEI) having a MW greater than 500 for a similar use. In U.S. Pat. No. 5,000,792 too poly(hydroxycarboxylic acid) amide derivatives with amines of the formula of NH2xe2x80x94Rxe2x80x2xe2x80x94N(Rxe2x80x3)xe2x80x94Rxe2x80x2xe2x80x3xe2x80x94NH2 are disclosed for use as pigment dispersing agent. WO95/17473 discloses poly(hydroxycarboxylic acid) amide derivatives with amines such as 3-dimethylaminopropylamine, ethylenediamine, poly(ethyleneimine) (PEI) having a MW greater than 500 and amines of the formula of NH2xe2x80x94Rxe2x80x2xe2x80x94N(Rxe2x80x3)xe2x80x94Rxe2x80x2xe2x80x3xe2x80x94NH2 for use in a method of preparing a non-aqueous dispersion of copper phthalocyanine. U.S. Pat. No. 4,349,389 discloses poly(hydroxycarboxylic acid) amide derivatives with amines such as 3-dimethyl-aminopropylamine, poly(ethyleneimine) (PEI) having a MW greater than 500 as dispersing agent in the preparation of a dispersible inorganic pigment composition. Finally, EP164817 disclose poly(hydroxycarboxylic acid) amide derivatives with polyamines(ethylenediamine, diethylenetriamine, etc.), aminoalcohols (diethanolamine, etc.) and ester derivatives with polyols (glycerol, etc.) for use as surfactant suitable for stabilising dispersions of solids in organic liquids and oil/water emulsions.
None of these patent documents, however, disclosed the use of poly(hydroxycarboxylic acid) amide or ester derivatives as fuel additive, acting as a detergent and as a lubricity additive in fuel compositions, which is therefore a further embodiment of the present invention.
The present invention further provides a fuel oil composition comprising a major amount of a fuel oil and a minor amount of a poly(hydroxycarboxylic acid)amide or ester derivative of formula I as defined above, and an additive concentrate suitable for addition to fuel oils which comprises a fuel-compatible diluent and a poly(hydroxycarboxylic acid)amide or ester derivative of formula I as defined above.
The poly(hydroxycarboxylic acid)amide or ester derivatives of formula I have useful application both in fuel compositions for spark-ignition engines (gasoline compositions) and in fuel compositions for compression ignition engines (diesel fuel compositions).
The xe2x80x9cminor amountxe2x80x9d referred to above is preferably less than 10% w of the composition, more preferably less than 1% w and advantageously less than 0.1% w (1000 ppmw) (parts per million by weight) of the composition. In preferred fuel compositions of the invention, the poly(hydroxycarboxylic acid)amide or ester derivative is present in an amount in the range 15 to 1000 ppmw of the fuel composition.
For gasoline compositions, the fuel will be a fuel boiling in the gasoline boiling range, and it may consist substantially of hydrocarbons or it may contain blending components. Alternatively, e.g. in countries such as Brazil, the fuel may consist substantially of ethanol.
Suitable liquid hydrocarbon fuels of the gasoline boiling range are mixtures of hydrocarbon boiling in the temperature range from about 25xc2x0 C. to about 232xc2x0 C., and comprise mixtures of saturated hydrocarbons, olefinic hydrocarbons and aromatic hydrocarbons. Preferred are gasoline mixtures having a saturated hydrocarbon content ranging from about 40% to about 80% by volume, an olefinic hydrocarbon content from 0% to about 30% by volume and an aromatic hydrocarbon content from about 10% to about 60% by volume. The base fuel is derived from straight run gasoline, polymer gasoline, natural gasoline, dimer and trimerized olefins, synthetically produced aromatic hydrocarbon mixtures, from thermally or catalytically reformed hydrocarbons, or from catalytically cracked or thermally cracked petroleum stocks, and mixtures of these. The hydrocarbon composition and octane level of the base fuel are not critical. The octane level, (R+M)/2, will generally be above about 85 (where R is Research Octane Number and M is Motor Octane Number).
Any conventional base gasoline can be employed in the practice of the present invention. For example, hydrocarbons in the gasoline can be replaced by up to a substantial amount of conventional alcohols or ethers, conventionally known for use in fuels. The base gasolines are desirably substantially free of water since water could impede a smooth combustion.
Normally, the gasolines to which the invention is applied may be leaded or unleaded, although are preferably substantially lead-free, and may contain minor amounts of one or more blending agents such as methanol, ethanol, tertiary butanol, ethyl tertiary butyl ether, methyl tertiary butyl ether, and the like, at from about 0.1% by volume to about 25% by volume of the base fuel, although larger amounts (e.g. up to 40% v) may be utilised. The gasolines can also contain conventional additives including antioxidants such as phenolics, e.g. 2,6-di-tert-butylphenol or phenylenediamines, e.g. N,Nxe2x80x2-di-sec-butyl-p-phenylenediamine, dyes, metal deactivators, dehazers such as polyester-type ethoxylated alkylphenol-formaldehyde resins. Corrosion inhibitors, such as that commercially sold by Rhein Chemie, Mannheim, Germany as xe2x80x9cRC 4801xe2x80x9d, or a polyhydric alcohol ester of a succinic acid derivative having on at least one of its alpha-carbon atoms an unsubstituted or substituted aliphatic hydrocarbon group having from 20 to 500 carbon atoms, for example, pentaerythritol diester of polyisobutylene-substituted succinic acid, the polyisobutylene group having an average molecular weight of about 950, in an amount from about 1 ppmw to about 1000 ppmw, may also be present. The fuels can also contain antiknock compounds such as methyl cyclopentadienylmanganese tricarbonyl, tetraethyl lead or other lead-containing compounds, and ortho-azodiphenol as well as co-antiknock compounds such as benzoyl acetone.
An effective amount of one or more poly(hydroxycarboxylic acid)amide or ester derivatives of formula I are introduced into the combustion zone of the engine in a variety of ways to prevent build-up of deposits, or to accomplish the reduction of intake valve deposits or the modification of existing deposits that are related to octane requirement. As mentioned, a preferred method is to add a minor amount of one or more poly(hydroxycarboxylic acid)amide or ester derivatives of formula I to the gasoline. For example, one or more poly(hydroxycarboxylic acid)amide or ester derivatives of formula I are added directly to the gasoline or are blended with one or more carriers and/or one or more hydrocarbon-soluble alkali metal or alkaline earth metal salts and/or one or more additional detergents before being added to the gasoline.
The amount of poly(hydroxycarboxylic acid)amide or ester derivative of formula I used will depend on the particular variation of formula I used, the engine, the fuel, and the presence or absence of carriers, additional detergents and diluents.
The carrier, when utilised, may conveniently have an average molecular weight from about 250 to about 5000. Suitable carriers, when utilised, include hydrocarbon based materials such as polyisobutylenes (PIB""s), polypropylenes (PP""s) and polyalphaolefins (PAO""s), poly(internal olefins) PIO""s, all of which may be hydrogenated or unhydrogenated but are preferably hydrogenated, and alkylbenzenes; polyether based materials including alkylene oxide polymers, interpolymers, copolymers and derivatives thereof wherein the terminal hydroxyl groups have been modified by esterification or etherification such as polybutylene oxides (poly-BO""s), polypropylene oxides (poly-PO""s), polyethylene oxides (poly-EO""s), polyhexadecene oxides (poly-HO""s) and mixtures thereof (i.e. both (poly-BO)+(poly-PO), poly-PO-EO, and poly-BO-PO)); and mineral oils such as those sold by member companies of the Royal Dutch/Shell group under the designations xe2x80x9cHVIxe2x80x9d, xe2x80x9cXHVIxe2x80x9d, xe2x80x9cEDELEXxe2x80x9d, xe2x80x9cCATENEXxe2x80x9d, xe2x80x9cGRAVEXxe2x80x9d (Trade Marks), Exxon Naphthenic 900 sus mineral oil and high viscosity index oils in general. The carrier is preferably selected from PIB""s, poly-BO""s and poly-PO""s, poly-PO-EO""s with poly-PO""s and poly-PO-EO""s being the most preferred.
A particularly prepared carrier fluid comprises a combination of a polyalphaolefin having a viscosity at 100xc2x0 C. in the range 2xc3x9710xe2x88x926 to 2xc3x9710xe2x88x925 m2/s (2 to 20 centistokes) being a hydrogenated oligomer containing 18 to 80 carbon atoms derived from at least one alphaolefinic monomer containing from 8 to 16 carbon atoms, and a polyoxyalkylene compound selected from glycols, mono- and diethers thereof, having number average molecular weight (Mn) in the range 400 to 3000, the weight ratio polyalphaolefin: polyoxyalkylene compound being in the range 1:10 to 10:1.
The polyalphaolefins are primarily trimers, tetramers and pentamers, and synthesis of such materials is outlined in Campen et al., xe2x80x9cGrowing use of synlubesxe2x80x9d, Hydrocarbon Processing, February 1982, pages 75 to 82. The polyalphaolefin is preferably derived from an alphaolefinic monomer containing from 8 to 12 carbon atoms. Polyalphaolefins derived from decene-1 have been found to be very effective. The polyalphaolefin preferably has viscosity at 100xc2x0 C. in the range of 6xc3x9710xe2x88x926 to 1xc3x9710xe2x88x925 m2/s (6 to 10 centistokes). Polyalphaolefin having a viscosity at 100xc2x0 C. of 8xc3x9710xe2x88x926 m2/s (8 centistokes) has been found to be very effective.
Preferred polyoxyalkylene compounds for use in combination with these polyalphaolefins are described in EP-A-588429.
The carrier concentration in the final fuel composition is up to about 1000 ppm weight. When a carrier is present, the preferred concentration is from about 50 ppm by weight to about 400 ppm by weight, based on the total weight of the fuel composition. Once the carrier is blended with one or more compounds of formula I and any other desired components, the blend is added directly to the fuel or packaged for future use.
The hydrocarbon-soluble alkali metal or alkaline earth metal salt, when utilised, may be one of those described in WO 87/01126, and the compounds of formula I are particularly suitable for incorporation, as additional component, in fuel compositions as described in WO 87/01126. Preferred hydrocarbon-soluble alkali metal or alkaline earth metal salts are, however, alkali metal or alkaline earth metal salts of a succinic acid derivative. Such a salt of a succinic acid derivative, when utilised, will have as a substituent on one of its alpha-carbon atoms an unsubstituted or substituted aliphatic hydrocarbon group having from 20 to 200 carbon atoms. Alternatively, the succinic acid derivative will have as a substituent on one of its alpha-carbon atoms an unsubstituted or substituted hydrocarbon group having from 20 to 200 carbon atoms which is connected to the other alpha-carbon atom by means of a hydrocarbon moiety having from 1 to 6 carbon atoms, forming a ring structure. Suitable such salts are described for example in EP-A-207560 and in EP-A-491439.
The salts of the succinic acid derivative can be monobasic or dibasic. Monobasic salts in which the remaining carboxylic acid group has been transformed into an amide or ester group may also be used. Suitable alkali metal salts of a partial ester of an alkyl polyether alcohol with a succinic acid derivative are described in EP-A-491439.
Suitable metal salts include lithium, sodium, potassium, rubidium, caesium and calcium salts. Particularly preferred salts are described in EP-A-207560.
The aliphatic hydrocarbon substituent(s) of the succinic acid derivative is suitably derived from a polyolefin, the monomers of which have 2 to 6 carbon atoms. Thus, convenient substituents include polyethylene, polypropylene, polybutylenes, polypentenes, polyhexenes or mixed polymers. Particularly preferred is an aliphatic hydrocarbon group which is derived from polyisobutylene.
The hydrocarbon group may include an alkyl and/or an alkenyl moiety and may contain substituents. One or more hydrogen atoms may be replaced by another atom, for example halogen, or by a non-aliphatic organic group, e.g. an (un)substituted phenyl group, a hydroxy, ether, ketone, aldehyde or ester. A very suitable substituent in the hydrocarbon group is at least one other metal succinate group, yielding a hydrocarbon group having two or more succinate moieties.
The aliphatic hydrocarbon group should contain 20 to 200, preferably 35-150, carbon atoms. When a polyolefin is used as substituent the chain length is conveniently expressed as the number average molecular weight. The number average molecular weight of the substituent, e.g. determined by osmometry, is advantageously from 400 to 2000.
The succinic acid derivative may have more than one C20-200 aliphatic hydrocarbon group attached to one or both alpha-carbon atoms, but preferably it has one C20-200 aliphatic hydrocarbon group on one of its alpha-carbon atoms and on the other alpha-carbon atom either no substituent or a hydrocarbon of only a short chain length, e.g. C1-6 group. The latter group can be linked with the C20-200 hydrocarbon group forming a ring structure.
The gasoline compositions of the present invention may also contain one or more additional detergents. When additional detergents are utilised, the gasoline composition will comprise a mixture of a major amount of hydrocarbons in the gasoline boiling range as described hereinbefore, a minor amount of one or more compounds of formula I as described hereinbefore and a minor amount of an additional detergent selected from the group consisting of polyalkenyl amines, e.g. polybutyleneamines, such as xe2x80x9cKEROCOMxe2x80x9d polyisobutyleneamine, available ex BASF, Mannich amines, polyalkenyl succinimides, poly(oxyalkylene)amines, poly(oxyalkylene) carbamates, poly(alkenyl)-N-substituted carbamates, and mixtures thereof. As noted above, a carrier as described hereinbefore may also be included. The xe2x80x9cminor amountxe2x80x9d is preferably less than about 10% by weight of the total fuel composition, more preferably less than about 1% by weight of the total fuel composition and yet more preferably less than about 0.1% by weight of the total fuel composition.
The polyalkenyl amine detergents utilised comprise at least one monovalent hydrocarbon group having at least 50 carbon atoms and at least one monovalent hydrocarbon group having at most five carbon atoms bound directly to separate nitrogen atoms of a diamine. Preferred polyalkenyl amines are polyisobutenyl amines. Polyisobutenyl amines are known in the art and representative examples are disclosed in various us Patents including U.S. Pat. No. 3,753,670, U.S. Pat. No. 3,756,793, U.S. Pat. No. 3,574,576 and U.S. Pat. No. 3,438,757. Particularly preferred polyisobutenyl amines for use in the present fuel composition include N-polyisobutenyl-Nxe2x80x2, Nxe2x80x2-dimethyl-1,3-diaminopropane (PIB-DAP), OGA-472 (a polyisobutenyl ethylene diamine available commercially from Oronite), N-polyisobutenyl diethylene triamine (PIB-DETA) and N-polyisobutenyl triethylene tetramine (PIB-TETA).
The Mannich amine detergents utilised comprise a condensation product of a high molecular weight alkyl-substituted hydroxyaromatic compound, an amine which contains an amino group having at least one active hydrogen atom (preferably a polyamine), and an aldehyde. Such Mannich amines are known in the art and are disclosed in U.S. Pat. No. 4,231,759. Preferably, the Mannich amine is an alkyl substituted Mannich amine.
The polyalkenyl succinimide detergents comprise the reaction product of a dibasic acid anhydride with either a polyoxyalkylene diamine, a hydrocarbyl polyamine or mixtures of both. Typically the succinimide is substituted with the polyalkenyl group but the polyalkenyl group may be found on the polyoxyalkylene diamine or the hydrocarbyl polyamine. Polyalkenyl succinimides are also known in the art and representative examples are disclosed in various patent references including U.S. Pat. No. 3,443,918, EP-A-208560, DE-OLS 3,126,404, U.S. Pat. No. 4,234,435, U.S. Pat. No. 4,810,261, U.S. Pat. No. 4,852,993, U.S. Pat. No. 4,968,321, U.S. Pat. No. 4,985,047, U.S. Pat. No. 5,061,291 and U.S. Pat. No. 5,147,414.
Particularly effective succinimide detergents are those obtained by reacting at least one amine, with a polyalkenyl derivative of a monoethylenically unsaturated C4-10 dicarboxylic acid material in which the ratio of dicarboxylic acid moieties per polyalkenyl chain is not greater than 1.2:1 and the number average molecular weight (Mn) of the polyalkenyl chain is in the range from 1600 to 5000, e.g. as described in EP-A-587250.
Amines employed in the preparation of said succinimide detergents are preferably C1-30, more preferably C1-18, and especially C8-12, amines containing 1 to 8 nitrogen atoms. Such amines may be branched or unbranched, saturated aliphatic, primary or secondary amines, containing 1 to 8 nitrogens, preferably mono- or diamines, such as ethylamine, butylamine, sec. butylamine, diethylamine and 3-dimethylamino-1-propylamine, but including higher polyamines such as alkylene polyamines, wherein pairs of nitrogen atoms are joined by alkylene groups of 2 to 4 carbon atoms.
Poly(oxyalkylene)amines are described, for example, in U.S. Pat. Nos. 4,985,047 and 4,332,595, in EP-A-440 248, EP-A-310 875, EP-A-208 978, WO 85/01956 and WO 97/41092.
The poly(oxyalkylene) carbamate detergents comprise an amine moiety and a poly(oxyalkylene) moiety linked together through a carbamate linkage, i.e.,
xe2x80x94Oxe2x80x94C(O)xe2x80x94Nxe2x80x94xe2x80x83xe2x80x83(IX)
These poly(oxyalkylene) carbamates are known in the art and representative examples are disclosed for example in U.S. Pat. No. 4,191,537, U.S. Pat. No. 4,160,648, U.S. Pat. No. 4,236,020, U.S. Pat. No. 4,270,930, U.S. Pat. No. 4,288,612 and U.S. Pat. No. 4,881,945. Particularly preferred poly(oxyalkylene) carbamates for use in the present fuel composition include OGA-480 (a poly(oxyalkylene) carbamate which is available commercially from Oronite).
The poly(alkenyl)-N-substituted carbamate detergents utilised are of the formula:
Roxe2x80x94Axe2x80x94C(xe2x95x90O)xe2x80x94ORxe2x80x3xe2x80x3xe2x80x83xe2x80x83(X)
in which Ro is a poly(alkenyl) chain; Rxe2x80x3xe2x80x3 is a hydrocarbyl or substituted hydrocarbyl group; and A is an N-substituted amino group. Poly(alkenyl)-N-substituted carbamates are known in the art and are disclosed in U.S. Pat. No. 4,936,868 and in WO 97/41092.
The one or more additional detergents are added directly to the fuel boiling in the gasoline boiling range, blended with one or more carriers, blended with one or more acid derivatives of formula I, or blended with one or more acid derivatives of formula I and one or more carriers before being added to the fuel.
The concentration of the one or more additional detergents in the final fuel composition is generally up to about 1000 ppmw for each additional detergent. When one or more additional detergents are utilised, the preferred concentration for each additional detergent is from about 10 ppmw to about 400 ppmw, based on the total weight of the fuel composition, even more preferably from about 25 ppmw to about 250 ppmw, based on the total weight of the fuel composition.
Additive components can be added separately to the gasoline or can be blended with one or more diluents, forming an additive concentrate, and added to the gasoline together. Suitable gasoline-compatible diluents are hydrocarbons and mixtures of hydrocarbons with alcohols or ethers, such as methanol, ethanol, propanol, 2-butoxyethanol, methyl tert-butyl ether, or higher alcohols such as xe2x80x9cDobanol 91xe2x80x9d, (Trade Mark) available from member companies of the Royal Dutch/Shell group.
Preferably the diluent is an aromatic hydrocarbon solvent such as toluene, xylene, mixtures thereof or mixtures of toluene or xylene with an alcohol. Additionally preferred diluents include xe2x80x9cShellsol ABxe2x80x9d, xe2x80x9cShellsol Rxe2x80x9d, (Trade Marks) and low aromatic white spirit (LAWS), which are available from member companies of the Royal Dutch/Shell group.
For diesel fuel compositions, the fuel will be a diesel oil, which may be a hydrocarbon fuel (a middle distillate fuel oil), which may be a conventional fuel or a low-sulphur fuel having a sulphur concentration below 500 ppmw, preferably below 50 ppmw, advantageously below 10 ppmw. Diesel fuels typically have initial distillation temperature about 160xc2x0 C. and 90% point of 290-360xc2x0 C., depending on fuel grade and use. Vegetable oils may also be used as diesel fuels per se or in blends with hydrocarbon fuels.
Low-sulphur fuels will typically require a lubricity additive to reduce fuel pump wear.
Additive concentrates suitable for incorporating in diesel fuel compositions will contain the poly(hydroxycarboxylic acid)amide or -ester derivative of formula I and may contain a fuel-compatible diluent, which may be a non-polar solvent such as toluene, xylene, white spirits and those sold by member companies of the Royal Dutch/Shell Group under the Trade Mark xe2x80x9cSHELLSOLxe2x80x9d, and/or a polar solvent such as esters and , in particular, alcohols, e.g. hexanol, 2-ethylhexanol, decanol, isotridecanol and alcohol mixtures such as those sold by member companies of the Royal Dutch/Shell Group under the Trade Mark xe2x80x9cLINEVOLxe2x80x9d, especially xe2x80x9cLINEVOLxe2x80x9d 79 alcohol which is a mixture of C7-9 primary alcohols, or the C12-14 alcohol mixture commercially available from Sidobre Sinnova, France under the Trade Mark xe2x80x9cSIPOLxe2x80x9d.
Additive concentrates and diesel fuel compositions prepared therefrom may additionally contain additional additives such as corrosion inhibitors, flow improvers, low molecular weight amine co-detergents, polyisobutylene succinimides as defined in WO 98/42808, dehazers, e.g. alkoxylated phenol formaldehyde polymers such as those commercially available as xe2x80x9cNALCOxe2x80x9d (Trade Mark)7D07 (ex Nalco), and xe2x80x9cTOLADxe2x80x9d (Trade Mark)2683 (ex Petrolite; anti-foaming agents (e.g. the polyether-modified polysiloxanes commercially available as xe2x80x9cTEGOPRENxe2x80x9d (Trade Mark)5851, Q 25907 (ex Dow Corning) or xe2x80x9cRHODORSILxe2x80x9d (Trade Mark) (ex Rhone Poulenc)); ignition improvers (e.g. 2-ethylhexyl nitrate, cyclohexyl nitrate, di-tertiary-butyl peroxide and those disclosed in U.S. Pat. No. 4,208,190 at Column 2, line 27 to Column 3, line 21); anti-rust agents (e.g. that commercially sold by Rhein Chemie, Mannheim, Germany as xe2x80x9cRC 4801xe2x80x9d, or polyhydric alcohol esters of a succinic acid derivative, the succinic acid derivative having on at least one of its alpha-carbon atoms an unsubstituted or substituted aliphatic hydrocarbon group containing from 20 to 500 carbon atoms, e.g. the pentaerythritol diester of polyisobutylene-substituted succinic acid), re-odourants, biocidal additives, anti-wear additives; anti-oxidants (e.g. phenolics such as 2,6-di-tert-butylphenol, or phenylenediamines such as N,Nxe2x80x2-di-sec-butyl-p-phenylenediamine), metal deactivators and lubricity agents (e.g. those commercially available as EC831 (ex Paramins) or xe2x80x9cHITECxe2x80x9d (Trade Mark) 580 (ex Ethyl Corporation), or those described in WO 98/01516 or WO 98/16596).
Preferred low molecular weight amine co-detergents are C10-20 alkylamines. Aliphatic primary monoamines, particularly linear aliphatic primary monoamines, having 10 to 20 carbon atoms are particularly preferred. The alkylamine preferably has 10 to 18, e.g. 12 to 18, more preferably 12 to 16 carbon atoms. Dodecylamine is particularly preferred. Another particularly preferred group are the polyisobutylene succinimides disclosed in Wo 98/42808.
Unless otherwise stated, the (active matter) concentration of each additive in the diesel fuel is preferably up to 1 percent by weight more preferably in the range from 5 to 1000 ppmw (parts per million by weight of the diesel fuel). The (active matter) concentration of the compound of formula I in the diesel fuel is preferably 50 to 1000 ppmw.
The (active matter) concentration of the dehazer in the diesel fuel is preferably in the range from 1 to 20, more preferably from 1 to 15, still more preferably from 1 to 10 and advantageously from 1 to 5 ppmw. The (active matter) concentrations of other additives (with the exception of the ignition improver and the lubricity agent) are each preferably in the range from 0 to 20, more preferably from 0 to 10 and advantageously from 0 to 5 ppmw. The (active matter) concentration of the ignition improver in the diesel fuel is preferably in the range from 0 to 600 and more preferably from 0 to 500 ppmw. If an ignition improver is incorporated into the diesel fuel, it is conveniently used in an amount of 100 to 500 ppmw. If a lubricity agent is incorporated into the diesel fuel, it is conveniently used in an amount of 100 to 500 ppmw.
The diesel oil itself may be an additised (additive-containing) oil or an unadditised (additive-free) oil. If the diesel oil is an additised oil, it will contain minor amounts of one or more additives, e.g. one or more additives selected from anti-static agents, pipeline drag reducers, flow improvers (e.g. ethylene/vinyl acetate copolymers or acrylate/maleic anhydride copolymers) and wax anti-settling agents (e.g. those commercially available under the Trade Marks xe2x80x9cPARAFLOWxe2x80x9d (e.g. xe2x80x9cPARAFLOWxe2x80x9d 450; ex Paramins), xe2x80x9cOCTELxe2x80x9d (e.g. xe2x80x9cOCTELxe2x80x9d W 5000; ex Octel) and xe2x80x9cDODIFLOWxe2x80x9d (e.g. xe2x80x9cDODIFLOWxe2x80x9d V 3958; ex Hoechst).
The present invention still further provides a method of operating an internal combustion engine (e.g. a spark-ignition engine or a compression-ignition engine) which comprises introducing into the combustion chambers of said engine a fuel composition (e.g. a gasoline composition or diesel fuel composition, as appropriate) as defined above.
Use of poly(hydroxycarboxylic acid)amide or -ester derivatives of formula I as additives in fuels for internal combustion engines may result in attaining one or more of a number of effects such as inlet system cleanliness (intake valves, fuel injectors, carburettors), combustion chamber cleanliness (in each case either or both of keep clean and clean-up effects), anti-corrosion (including anti-rust) and reduction or elimination of valve-stick.
The invention will be further understood from the following illustrative examples in which Examples 1 to 6 relate to the preparation of poly(hydroxycarboxylic acid)amide or -ester derivatives of formula I.
Various abbreviations are employed in the examples as follows:
xe2x80x9cAVxe2x80x9d denotes acid value, and this was determined using a xe2x80x9cMetrohm 670xe2x80x9d(trademark) potentiometric titrometer according to a method based upon ASTM D 664-89 with modified solvent system (the product is first dissolved in a toluene/methyl ethyl ketone 60/40 weight/weight mixture, and then diluted with a tert-butanol/water toluene 38.8/2.9/58.2 weight/weight/weight mixture);
xe2x80x9cTBNxe2x80x9d denotes total basic nitrogen, and this was determined using a xe2x80x9cMetrohm 670xe2x80x9d(Trade Mark) potentiometric titrometer according to a method based upon ASTM D 2896 with modified solvent system (75w w toluene, 12.5% w acetonitrile, 12.5% w acetic acid);
xe2x80x9cmeqgxe2x88x921xe2x80x9d denotes milliequivalents per gram. In the examples and tests which follow, all parts and percentages are by weight unless stated otherwise, and temperatures are in degrees Celsius.
Commercial 12-hydroxystearic acid (referred to in the examples as xe2x80x98HSaxe2x80x99, ex Oleotec) used in the following examples contains 1% palmitic acid, 10% stearic acid (referred to in the examples as xe2x80x98Saxe2x80x99), 4% 12-ketostearic acid as impurities. Commercial ricinoleic acid (Nouracid CS80 ex Akzo Nobel) has an acid value of 175 mg KOH/g and hydroxyl value of 150 mg KOH/g.